n 2001 PubMed will undergo changes to the display formats and some search options. These changes are made possible by the capabilities of PubMed, NLM's new Data Creation and Maintenance System (DCMS), and other reinvention initiatives. The DCMS is where MEDLINE records are built, indexed, and corrected. A description of the PubMed changes follows according to the date the change is expected in 2001. The letters in parentheses following the field names are the field abbreviations for the MEDLINE format.

Changes expected by late January 2001:

2001 MeSH
In late January we expect to reload MEDLINE citations with 2001 MeSH vocabulary into PubMed.

MEDLINE Unique Identifier (UI)
The MEDLINE Unique Identifier (UI) will display only on the tagged formats (i.e., MEDLINE and XML). The UI will be searchable for the foreseeable future. Note: The PubMed Unique Identifier (PMID) will not change. It will remain as the unique identifying number for all PubMed citations.

Copyright Information (CI)
If publishers supply their citation data to us electronically, they may include a copyright statement for the abstract. In the past this information was included at the end of the abstract. Prospectively, NLM is putting this statement in the new Copyright Information (CI) field of the tagged formats (i.e., MEDLINE and XML). In non-tagged formats (e.g., Abstract) the copyright statement will be placed at the end of the abstract.

Date Created (DA)
The old Date of Entry field will be replaced by the new Date Created field and will retain DA as the field abbreviation. The Date Created field will indicate the date that processing in the DCMS began for the record. (It is not the same as the Entrez Date (EDAT) which is the date the record entered PubMed.) This field will be in a YYYYMMDD format, e.g., 20010112. See also Date Completed below. This field will display only on tagged formats, (i.e., MEDLINE and XML).

Date Completed (DCOM)
This new field will indicate the date that processing in the DCMS was completed for the record. See also Date Created above. For retrospective MEDLINE citations this date will match Date Created. This field will be in a YYYYMMDD format, e.g., 20001019. This field will display only on tagged formats (i.e., MEDLINE and XML).

Date Revised (LR)
The old Last Revision Date (LR) and Class Update Date (CU) are being replaced by the Date Revised field which will retain LR as the field abbreviation. This field will be in a YYYYMMDD format. All MEDLINE citations in PubMed at the time of the 2001 update in late January will display the date 20001218 in the Date Revised field. New citations will not display a date in this field. If a citation is revised in the future, this field will reflect the date of that change. This field will display only on tagged formats (i.e., MEDLINE and XML).

Date of Electronic Publication (DEP)
This new field will contain the date an article was published electronically if there is also a traditional, hard copy date of publication (DP). This field will display only on tagged formats (i.e., MEDLINE and XML).

Journal Title Code (JC)
This field is in transition. In late January PubMed citations will have a new field, the NLM Unique ID (see below). Citations from journals new to PubMed will no longer be assigned a three-character Journal Title Code. Citations from "new" journals will repeat the NLM Unique ID in the JC field, which displays only on the tagged formats (i.e., MEDLINE and XML). We expect the JC field will be discontinued in 2002.

NLM Unique ID (JID)
This new field will contain a 7 or 9-digit number assigned to the journal by NLM's Integrated Library System accessed via LocatorPlus. This field will display only on tagged formats (i.e., MEDLINE and XML). This field is not searchable. Journals can be searched using the title abbreviation, the full journal name, or the ISSN number.

Discontinued Fields
The following is a list of fields that will no longer display on the tagged formats of PubMed records after late January 2001:

Changes to the Author (AU) Field
NLM has manipulated author data in three ways to improve consistency and aid retrieval:

1. All periods will be removed.
   
   

   St. Clair M

   becomes

   St Clair M

   
   
2. The older forms for "second" and "third" which were abbreviated as "2d" and "3d" will be converted to "2nd" and "3rd" in line with current rules for author names.
   
   

   Smith AB 3d

   becomes

   Smith AB 3rd

   
   
3. Older rules for the author name format put certain name particles after the initials; these hanging particles will be moved to the beginning of the surname.
   
   

   Vaart JM van der

   becomes

   van der Vaart JM

   
   

Total Record Count
The 2001 MEDLINE reload (1966 through the last update for 2000) will contain 10,726,231 [corrected] citations. This number is slightly less than before for two reasons:

1. 22,267 monographic chapter citations created mostly in the late 1970s were removed and will be added to LocatorPlus.
   
   
2. About 500 [corrected] citations, mostly from 1966 - 74, were removed because NLM cannot identify the serial title.

Citation Subset (SB)      [section replaced on February 8, 2001]
The Special List Indicator (LI) field and Journal Subset (SB) field will be replaced by a new searchable field called Citation Subset. This multiply-occurring field will display on the tagged formats (i.e., MEDLINE and XML).

There are three types of citation subsets. Journal, subject, and PubMed citation status. PubMed's Limit screen has a Subset pull-down menu where some of these subsets can be selected; alternatively the citaton subset can be incorporated into a search query by entering a Citation Subset value.

Journal Citation Subsets are now available with the initial reload of citations with 2001 MeSH vocabulary. The following list shows the possible journal Citation Subset values with an explanation of each. Several are closed subsets no longer being assigned to current data. One, X, will increase when the unique journal citations from AIDSLINE are added to PubMed.

You are able to search journal subset values using jsubset? where ? stands for a journal subset value and no qualifier is needed.

Example:

asthma AND jsubsetd    (limits to dental journals subset)

Please note that the value for Abridged Index Medicus has changed from jsubseta to jsubsetaim.

There are now three subject subsets on PubMed. AIDS, Toxicology, and a new subset for Complementary Medicine. Subject subsets may be selected from the Subset pull-down menu in Limits, or searched as aids, tox, or cam - retaining the [SB] search tag:

Example:

vaccination AND aids [sb]

The Citation Subset values for the status of a citation will change in the future, however, these values can be selected from the Subset pull-down menu in Limits, or searched directly with the [SB] search tag (see Status Tags).

Note: Citations that do not display any Citation Subset data are publisher-supplied or are out of scope for MEDLINE (not indexed). In-process citations may have some Citation Subset data; however, these data may not be complete until the citation has completed indexing.

[end replacement]

Changes expected during the first quarter of 2001
(Implementation dates to be announced in PubMed's New/Noteworthy section):

Country of Publication (CY)
The Country of Publication for a citation indicates the country in which the journal is published. Citations added to PubMed prior to the January 2001 reload will retain existing CY data. CY data on citations created for or after the January 2001 reload will come from the 044 MARC field in the record for the journal in NLM's online catalog (LocatorPlus). The CY values have been created using the country names in the Z branch of the MeSH tree (Geographic Locations). The CY data are not the same as a MeSH term for a country which is assigned to a citation when the geographical location is important to the research reported in the article. Nor do the CY data represent where the research was conducted. Also, remember that one journal may be published in several places over its lifetime, and there is no guarantee that such changes are noticed or recorded by NLM. In fact, Country of Publication has always been subject to certain assumptions and users are advised to be cautious in their interpretation of CY data.

The CY field has always displayed on the tagged formats (i.e., MEDLINE and XML), however, it will be searchable using the [CY] search tag.

Search example to find citations about Mad
Cow Disease in journals published in France:

          mad cow disease AND france [cy]

Collective Name (CN)
This is a new field for the corporate authorship of an article. If present, it will appear following the author names separated by a semi colon, or if there are no author names, in that part of the citation.

Example:

McGovern TW, LaWarre SR, Brunette CT; American Medical Association.

These names will display exactly as they appear in the journal, i.e., we will not edit the names to standardize them nor translate them into English. This field will display on all formats and will be searchable using the [CN] search tag. Older citations will retain corporate names at the end of the title field [TI].

Comments/Corrections
Information about retractions, errata, comments, updates, and republications will display on PubMed citations in newly created fields known collectively as the Comments/Corrections fields. Below is a list of the new fields. An asterisk (*) indicates the field will not display on the Summary format.

Example of a citation showing Comment data:
Arthritis Rheum 2000 Aug;43(8):1902-3. Comment on: Arthritis Rheum 2000 Jan;43(1):14-21.

Status Tags on PubMed Citations

NLM plans to change how citations are labeled in PubMed. Currently on the citation you see:

• [Record as supplied by publisher] - on citations either recently entered into PubMed, or out of scope for MEDLINE.
• [MEDLINE record in process] - on citations undergoing bibliographic data quality review and indexing.
• No tag indicates the citation has been indexed and the bibliographic data has been reviewed.

During the first quarter of 2001 we will change procedures and the following status tags will display on PubMed citations:

[PubMed - as supplied by publisher]

[PubMed - in process]

[PubMed - indexed for MEDLINE]

[PubMed]

Although we have not confirmed the display format we expect it will be similar to the examples shown below.

PubMed - as supplied by publisher
The tag, [PubMed - as supplied by publisher], will be displayed under one of three conditions, but in all cases the citation is in the form exactly as received from the publisher and may include errors in the bibliographic data such as misspellings of author names, incorrect page numbers, etc.

Condition 1: The citation was recently added to PubMed via electronic submission from the publisher.

Condition 2: The citation is from a journal not indexed for MEDLINE.

Condition 3: The citation is from a journal that was accepted for MEDLINE after this citation's publication date (for more information about the journal, check LocatorPlus).

Example in Summary format:

Lo CM, Fan ST.

Surgical techniques in right lobe liver transplantation.

Transplant Proc. 2000 Nov;32(7):1512-1513. No abstract available.

PMID: 11119811           [PubMed - as supplied by publisher]

You will be able to limit to these citations in a search using the "Publisher" subset on the Limits screen, or directly in a search with the Subset search tag, [SB].

Example:             premature labor AND publisher [sb]

PubMed - in process
The tag, [PubMed - in process], will indicate the citation has been sent to the DCMS where it can be: reviewed for accuracy of the bibliographic data and indexed, i.e., the article will be reviewed by MeSH indexers and MeSH vocabulary will be assigned (if the subject of the article is within the scope of MEDLINE).

Example in Summary format:

Plante-Bordeneuve V, Said G.

Transthyretin related familial amyloid polyneuropathy.

Curr Opin Neurol. 2000 Oct;13(5):569-73.

PMID: 11073365           [PubMed - in process]

You will be able to limit to these citations using the "In process" subset on the Limits screen, or directly in a search with the Subset search tag, [SB].

Example:           premature labor AND in process [sb]

Note: PREMEDLINE will no longer exist as a separate database.

PubMed - indexed for MEDLINE
The tag, [PubMed - indexed for MEDLINE], will indicate the citation:

• is for an article within the scope of MEDLINE, and
• has been indexed with MeSH, Publication Types, Registry Numbers, etc., and
• has been reviewed for accuracy of the bibliographic data

Example in Summary format:

Broughan TA, Soloway RD.

Acetaminophen hepatoxicity.

Dig Dis Sci. 2000 Aug;45(8):1553-8.

PMID: 11007105           [PubMed - indexed for MEDLINE]

You will be able to limit to these citations using the "MEDLINE" subset on the Limits screen, or directly in a search with the Subset search tag, [SB].

Example:           sleep paralysis AND medline [sb]

PubMed
The tag, [PubMed], will be on a citation for an article in a journal from which NLM regularly indexes articles, but this article is on a topic considered outside the scope of MEDLINE. The bibliographic data will have been reviewed for accuracy.

Example in Summary format:

Monnin E, Indermuhle A, Dallenbach A, Fluckiger J, Stauffer B, Stocker TF, Raynaud D, Barnola JM.

Atmospheric CO2 concentrations over the last glacial termination.

Science. 2001 Jan 5;291(5501):112-4.

PMID: 11141559           [PubMed]

You will be able to limit to these citations directly in a search with the Subset search tag [SB].

Example: volcano AND pubmed [sb]

By Annette M. Nahin
MEDLARS Management Section
and
Lou Knecht
Bibliographic Services Division

Nahin AM, Knecht L. Changes to PubMed for 2001. NLM Tech Bull. 2001 Jan-Feb;(318):e2.